Clinical surgeons have a limited number of options when reconstructing bone defects that result from congenital anomalies, trauma, infection and/or oncologic resection. Current bone-graft implantation techniques and materials each have limitations. For this reason, I aim to improve bone grafting materials that will recruit cells from the surrounding tissue and promote osteogenic differentiation, part of the natural bone regeneration process, by investigating how human mesenchymal stem cells (hMSCs) receive information from their microenvironments. Topographic cues have been shown to influence cell adhesion, motility, proliferation, protein expression, gene regulation and differentiation of hMSCs. A thiol-ene based photopolymerization scheme developed in the Bowman-Anseth laboratories will be used to create biomaterials containing cell adhesion mimics and enzymatically and photo-degradable linkages that allow for the creation of topographies using precise spatial erosion. The proposed research aims to engineer improved bone grafting materials by investigating how incorporating topographic cues into a polymer scaffold that contains cell adhesion mimics and enzymatically degradable linkages influences osteogenic differentiation. I hypothesize that differentiation will depend on dynamic changes in their microenvironment that will be achieved through the photolabile chemistry. Two specific aims are outlined: Aim 1: Identify topographic features and spatial arrangements in thiol-ene polymer scaffolds that promote osteogenic differentiation of hMSCs. Aim 2: Examine the effects of changing the spatial arrangement of topographic features in real-time on osteogenic differentiation. Completion of these aims will significantly advance our understanding of the mechanisms for how topography induces MSC differentiation. The versatility of this polymer system and approach allows us to conduct unique experiments for hMSC culture and improve our understanding of material systems that can be easily tailored for tissue regeneration applications based on stem cell delivery or homing.